The present invention generally relates to a semiconductor device. More specifically, the present invention is directed to a semiconductor device suitably designed for mounting a plurality of semiconductor elements in a stack manner.
Semiconductor devices, especially, semiconductor memories have been used in various sorts of information appliances such as large-scaled computers, personal computers, and portable appliances, while memory capacities required thereof are increased year by year. On the other hand, mounting areas of these semiconductor memories are increased in connection with large memory capacities, which may cause a certain factor to impede compactnesses of these information appliances. Under such a circumstance, various techniques capable of mounting semiconductor memories in high mounting density have been developed. As techniques capable of realizing memories having large storage capacities within limited mounting areas, for instance, JP-A-11-40745, JP-A-8-236694, and JP-A-2000-286380 describe such a technical idea that semiconductor packages are stacked on mounting substrates. Also, U.S. Pat. No. 3,648,131, U.S. Pat. No. 6,141,245, U.S. Pat. No. 5,229,647, JP-A-59-222954, JP-A-61-88546, and JP-A-63-156348 disclose such a technical idea that a plurality of semiconductor elements are mounted in a stack manner within a single semiconductor package, and then, the stacked semiconductor elements are connected to each other by employing through holes formed in the semiconductor elements.
However, in the case that a plurality of DRAMs are mounted in a stack manner within a single semiconductor package, a heat value of the entire semiconductor package becomes large, as compared with that of a semiconductor package on which a single sheet of DRAM is mounted. As a result, there are certain risks as to operation failures and destruction of semiconductor elements, which are caused by temperature increases during operations of the semiconductor devices.